Design and Optimization of Bed of Nails Unit Cell for Broadband Groove Gap Waveguide Applications

This article presents a comprehensive study on the design and optimization of Bed of Nails (BON) unit cell for Groove Gap Waveguide (GGW) applications, spanning a frequency range from 1 GHz to 40 GHz. The BON unit cell, consisting of a metal pin with top and bottom parallel metal plates, is crucial for achieving wide bandgap. Key design parameters, including width and height of metal pin, gap between the top of metal pin and top parallel metal plate usually referred as air gap, and the period of the unit cell, significantly influence the dispersion characteristics and overall bandgap. This study provides detailed parametric relationships for these dimensions, demonstrating their interdependencies and impact on bandgap enhancement. The optimized unit cell design is applied to GGW applications, focusing on critical distance between the side wall and the nearest metal pin, resulting in a 15.23% bandwidth enhancement compared to state-of-the-art designs. A mechanical study has also been incorporated to evaluate the influence of atmospheric conditions, particularly wind loading, on the surface of the developed RF device. This assessment is performed in accordance with international manufacturing standards for antenna structures, as specified in ANSI/TIA-222-H. A custom built prototype device was fabricated and tested, confirming accuracy of results across 1 GHz to 40 GHz spectrum. This research offers valuable insights and practical guidelines for researchers aiming to design efficient GGW based devices, simplifying design process while enhancing performance and fabrication efficiency. Consequently, it contributes to the field of microwave and millimeter-wave (mm-wave) engineering.